The aforementioned technique is known as postgrafting and is well known, particularly in the treatment of textile materials. This technique is particularly useful in conferring desired permanent properties to the polymeric material which is grafted. In document EP 0 299 808, for example, the treatment is intended for waterproofing the textile material.
There are many activation methods such as for example the action of ozone or of ammonium sulphate as in document EP 0 299 808. Further, the irradiation under inert atmosphere as disclosed in U.S. Pat. No. 3,912,499.
The activation may also be achieved by electric treatments said electric treatments being one of corona discharge or plasma. However, these type of treatments have certain limitations. For example, the action of the electric treatment may result in the creation of free radicals on the surface of the polymeric material, also stray reactions and in particular a certain amount of degradation of the macromolecular structure of the material and crosslinking reactions which modify the initial characteristics of the material. Consequently, if the material is to be protected against a deterioration caused by said stray reactions, the grafting rate obtained will necessarily be low resulting in grafting kinetics which are slow.